let watermark = {};
const idd = "1.234523841642.1234124163";
var _interval = null;
let setWatermark = (str) => {
  let id = idd;
  if (document.getElementById(id) !== null) {
    document.body.removeChild(document.getElementById(id));
  }
  // 创建一个画布
  let can = document.createElement("canvas");
  // 设置画布的长宽
  can.width = 100;
  can.height = 100;
  let cans = can.getContext("2d");
  // 设置旋转角度
  cans.rotate((-20 * Math.PI) / 180);
  cans.font = "14px Vedana";
  // 设置填充绘画的颜色、渐变或者模式
  cans.fillStyle = "rgba(200, 200, 200, 0.70)";
  // 设置文本内容的当前对齐方式
  cans.textAlign = "center";
  // 设置在绘制文本时使用的当前文本基线
  cans.textBaseline = "Middle";
  // 在画布上绘制填色的文本（输出的文本，开始绘制文本的X坐标位置，开始绘制文本的Y坐标位置）
  cans.fillText(str, can.width / 3, can.height / 2);
  let div = document.createElement("div");
  div.id = id;
  div.style.pointerEvents = "none";
  div.style.top = "20px";
  div.style.left = "0px";
  div.style.position = "fixed";
  div.style.zIndex = "100000";
  div.style.width = document.documentElement.clientWidth + "px";
  div.style.height = document.documentElement.clientHeight + "px";
  div.style.background =
    "url(" + can.toDataURL("image/png") + ") left top repeat";
  document.body.appendChild(div);
  return id;
};
// 该方法只允许调用一次
// 添加水印的方法
watermark.set = (str) => {
  let id = setWatermark(str);
  _interval = setInterval(() => {
    if (document.getElementById(id) === null) {
      id = setWatermark(str);
    }
  }, 500);
  window.onresize = () => {
    setWatermark(str);
  };
};
// 移除水印的方法
watermark.remove = () => {
  if (document.getElementById(idd) !== null) {
    var box = document.getElementById(idd);
    box.parentNode.removeChild(box);
    _interval ? clearInterval(_interval) : "";
  }
};
export default watermark;
